Process for producing titanium carbide



United States Patent PROCESS FOR PRODUCING TITANIUM CARBIDE Leif Aagaard, Plainfield, N .J assignor to National Lead Company, New York, N.Y., a corporation of New Jersey No Drawing. Original application Aug. 16, 1954, Ser. No. 450,234, now Patent No. 2,819,152, dated Jan. 7, 1958. Divided and this application Apr. 16, 1957, Ser- No. 653,075

2 Claims. (Cl.23-208) The present invention relates in general to a process for making metalloids and more especially to an improvement in the method of forming a starting composition from which the metalloids may be formed; this application being a divisional application of co-pending application S.N. 450,234 filed August 16, 1954 now Pat. No. 2,819,152.

An object of the present invention is to provide an improved method for forming a homogeneous mixture of a hydrated titanium compound and carbon particles for use in the preparation of metalloids.

A further object of the invention is to produce a starting composition for the preparation of metalloids by forming a hydrated titanium compound in the presence of carbon.

These and other objects, features and advantages of the invention will be described and explained more fully in the following detailed description of a preferred form of the invention.

In its broadest aspects, the instant invention relates to a starting composition for the preparation of metalloids comprising an intimate mixture of a hydrated titanium compound and carbon particles; and to a method for producing the starting composition by precipitating the hydrated titanium compound in the presence of the carbon particles such that the hydrated titanium compound and carbon particles are joined by a coalescent bond.

As used herein, the term hydrated titanium compound shall be understood to denote and to include not only the raw hydrous titanium oxide pulp, which is formed and precipitated from a salt solution of titanium by hydrolysis, but also modifications thereof, such as, for example, a hydrous titanium phosphate or an alkali altered hydrous titanium oxide.

The raw hydrous titanium oxide is an uncalcined hydrolysate precipitated usually by hydrolysis from a salt solution prepared from an acid digest of a titaniferous material, such as, for example, titaniferous ore, ore concentrates or slags. By way of illustration, the digestion treatment may comprise mixing a titaniferous material with concentrated (93%) sulfuric acid in an amount such that the ratio of acid, calculated as 100% sulfuric acid, to the titaniferous material, on a TiO basis, is within the range of from about 1.3 to 1.5 parts acid to one part titaniferous material, and heating the mixture until a reaction sets in and a digestion cake is formed. The digestion cake is then dissolved in water to form a solution to which scrap iron or the like is added to convert the ferric iron values to ferrous iron. The solution is then clarified, filtered, concentrated'and crystallized in the manner wellknown to the art of pigment manufacture to form a titanium sulfate solution from which the hydrous titanium oxide is precipitated by hydrolysis and thereafter washed.

Although washing serves to remove large amounts of soluble salts and free acid, there is usually some acid present in the form of a basic salt or adsorbed acid which may impair the quality of metalloids to be formed therefrom, and hence the hydrate may be treated with a basic substance, such as the alkaline compounds of sodium, potassium or ammonium to neutralize and/ or remove the adsorbed acid. In general, the size of the individual par- 3,004,832 Patented Oct. 17, 1961 ICC ticles, that is to say the crystalloids or groups of crystalloids of precipitated hydrous titanium oxide, is within the range of from about 0.01 to 0.2 micron. For reasons of economy, sulfuric acid solutions of titanium are used in carrying out the process of the instant invention in preference to solutions prepared from hydrochloric acid.

UNALTERED HYDRATE To prepare the starting composition of this invention using a raw unaltered hydrous titanium oxide pulp, finely divided carbon having a particle size in the range of from 0.005 to 0.01 micron and preferably hydrophilic, is added to a titanium sulfate solution prepared in the manner hereinabove described, prior, to hydrolysis, whereupon the mixture is heated and maintained at a temperature within the range of about C. to about 112 C. for about two hours until a major portion of the titanium oxide values in the solution is hydrolyzed and precipitated out as hydrous titanium oxide in the presence of the individ ual carbon particles. Thereby, the individual particles of hydrous titanium oxide are joined with the individual carbon particles by a coalescent bond to form a uniform intimate mixture of the hydrate and carbon. This mixture is then filtered or otherwise separated from the hydrolysis acid, washed and subsequently dried to provide a starting composition from which metalloids may be formed as described below, the size of the particles of the starting composition being within the range of from about 0.02 to 0.5 micron.

While the procedure described above is satisfactory, improved yields of the hydrate may be obtained by the eX- pedient of adding a nucleating agent to the salt solution at hydrolysis. A typical nucleating agent, some times referred to in the art as a yield seed, is that pre- Although the hydrous titanium oxides formed from a titanium sulfate solution, as hereinabove described, are highly satisfactory, modified hydrates of titanium may be used. Thus, it is within the purview of the instant invention to prepare a starting composition by mixing a dilute solution of phosphoric acid and a dilute titanium salt solution at room temperature in the presence of finely divided carbon, and then heating the mixture to complete the reaction and form a filterable starting compound comprising individual particles of titanium phosphate joined to the individual carbon particles by a coalescent bond; or by adding phosphoric acid or a soluble phosphate to the unmodified starting compositions hereinabove described, thereby to convert the hydrous titanium oxide component to titanium phosphate in the presence of the carbon.

While the formation of the starting material of this invention by thermal hydrolysis of a sulfate solution in the presence of carbon may be carried out successfully at atmospheric pressure, it has been found that the rate of hydrolysis may be accelerated considerably by can-ying out the operation in an autoclave under pressures of the order of from 100-500 lbs. per square inch. Pressure hydrolysis, preferably coupled with agitation, results in a thorough blending of the hydrate and carbon particles in a relatively short time.

To further illustrate this invention, the following examples are given:

3 Example I a To prepare the unmodified starting composition of this i nt n a c rified ul a e so uti n, Prepa ed in. a mann r wellrknewn in t a t. s for; e ample by i es n a titaniferous Ore n. eq e abeted H2894 to orm. a a e which is b t it H2O fil er d. c ar fi d. c st l ze nd again uted b 2 to f m a a uhavin a T 02 c n nt f abeut .9 r m peri er. To this solution was added finely divided hydrophilic carbon in an amount which was varied depending upon he t p o et e to be o me er f em- Thu when he sa utibn a be s o repare titanium, a b e inely i id y p ili carb s a ded to the .11 ies. in an mount o at sfy he ormula;

ba e on he amo n o iteniumiba eulated. as I Qe, r Co ered from the solution.

A s luti P pa e in e bb e ma ner was: b led or b u two rs n he pr ense 9f. 1% Y e d. seed un i ab t 95% the t an m as Pree ni at deut s a it nie, hyd t mat y so ated ith. tbefi-ne eer e es qt ee be h s ar n c po ion. as then s para ed rom he qui a h d. nd dr ed an ubsequent y c verte to t n m c r de y eale aat et To h end he s n mp iti u w s pla e in a urn efld ci a a empera ure o a out 5 for about two hours in an inert atmosphere. The result: ing product comprised a finely divided powder, the size Qff be pa i s ein r 1 to 0. micr ns n analy of the product showed 80% titanium and 19.5%. carbon.

Examalell To prepare a titanium boride metalloid a starting-composition was prepared substantially in the manner de-. scribed in Example I except that in this instance finely divided hydrophilic carbon was added to the sulfate solution prior to hydrolysis in an amount to satisfy the formula:

' xam- The resulting product comprised a; finely divided powder which analyzed 68.4% titanium and 29.6% boron and had an effective particle sizeof from 1 to 5 microns.

amp e II To prepare a titanium nitride metalloid, a starting composition was formed by the method described in Example I except that. in this instance finely divided hydrophilic carbon was added to the sulfate solution in an amount to satisfy the formula:

basedon the amount of titanium, calculated as 110 recovered from the solution. The starting composition resulting from hydrolysis of this solution was dried and introduced into a furnace and calcined at a temperature of about 1350 C. for about two hours in an atmosphere of 'nitrogen. The resulting product comprised a finely divided'titanium nitride powder which analyzed 78.6% titanium and 19.4% nitrogen, the size of the particles being from 1 to microns.

4 Example IV To prepare titanium carbide from a modified starting composition comprising phosphate and hydroph li a b n, a dil te ut on at pho pho i ac d (5 r m per i e 32%) w s add a a i ni m ate so u n; 0 rams b liter; iOs), he ght. ratiQ of P 0 to the titanium values being 0.6 on a TiO basis. The finely divided carbon. was added in an amount to. satisfy the formulaz' Example, V

To prepare, the titanium nitride metalloid from a start-i ing composition of coalesced titanium phosphate and hydrophilic carbon, a starting composition was prepared substantially in the manner described in Example IV except that finely divided carbon was. added in an amount to satisfy the formula: N

b ed. on th amo nt o tanium, calcu a e at z 'a recovered; from the, solution. This starting composition was calcined at atemperature of about; 135 0 C for two. hours in an atmosphere of nitrogen-., The resulting prod uct was a finely divided titanium nitride powder of sub. stantially uniform particle size, which analyzed 79% titanium and 21% nitrogen, the particles. ranging in size from about 1 to 10 microns.

E a p e To form a titanium boride metalloid, a starting composition of titanium phosphate and hydrophilic carbon was prepared as described in Example IV except that fine- 1y divided carbon was added in an amount tosatisfy the formula:

basedon the amount of titanium, calculated as Ti0 re-t covered from the solution. Forevery 148 parts of tie; tanium, calculated as TiO in the titaniumephosphate-v carbon composition were added l3t1 parts. boric acid as. B 0 The mixture was thoroughly agitated for a suf= ticientlen-gth of time to form intimate contact of the materials whereupon the mixture was introduced into a furnace and calcined at a temperature of about 1550 C. for about two hours in an atmosphere of argon.

The resulting product comprised finely divided powder which analyzed 68.1% titanium and 29.9%. boron, the efiective particle size being from 1 to 5 microns.

From the foregoing description and examples it will be. evident that the instant invention provides a starting composition for the production of finely divided metal-,- loids, the starting composition being characterized by a coalescent bond between the hydrated titanium com-. pound and carbon such that themetalloids formed there-. from are of high purity and uniform and line particle size, the methods for producing the starting compositions being characterized by precipitating the hydrous titanium oxide in the presence of the carbon particles, thereby to insure a highly reactive material which may be calcined at relatively low temperatures to form metalloids of superior physical and chemical characteristics.

While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other variations and modifications may be employed within the scope of the following claims.

I claim:

1. Process for forming a titanium compound of carbon, the steps of: preparing a starting composition by forming a sulfate solution of titanium, hydrolyzing said sulfate solution in the presence of finely divided carbon particles to form a mixture comprising coalesced particles of a hydrated titanium compound and carbon, adding a soluble inorganic phosphate to the mixture to convert said hydrated titanium values of said mixture to titanium phosphate, and then calcining said mixture to form a finely divided titanium compound of carbon.

2. Process for forming a titanium compound of carbon, the steps of: preparing a starting composition by forming a sulfate solution of titanium, adding finely divided carbon particles to the said sulfate solution in an amount such that the weight ratio of carbon to titanium values in said solution, calculated as TiPgOq, is in the range of from 7 to 10, admixing phosphoric acid with said mixture of carbon and titanium salt solution, and hydrolyzing said admixture to form and precipitate an admixture comprising coalesced particles of titanium phosphate and carbon, and then calcining said admixture to form a finely divided titanium compound of carbon.

References Cited in the file of this patent UNITED STATES PATENTS 2,733,134 Aagaard et a1. Jan. 3-1, 1956 

1. PROCESS FOR FORMING A TITANIUM COMPOUND OF CARBON, THE STEPS OF: PREPARING A STARTING COMPOSITION BY FORMING A SULFATE SOLUTION OF TITANIUM, HYDROLYZING SAID SULFATE SOLUTION IN THE PRESENCE OF FINELY DIVIDED CARBON PARTICLES TO FORM A MIXTURE COMPRISING COALESCED PARTICLES OF A HYDRATED TITANIUM COMPOUND AND CARBON, ADDING A SOLUBLE INORGANIC PHOSPHATE TO THE MIXTURE TO CONVERT SAID HYDRATED TITANIUM VALUES OF SAID MIXTURE TO TITANIUM PHOSPHATE, AND THEN CALCINING SAID MIXTURE TO FORM A FINELY DIVIDED TITANIUM COMPOUND OF CARBON. 